1-Thiadiazolyl-5-pyridylcarbonyloxyimidazolidinones

ABSTRACT

This invention discloses new compounds of the formula ##STR1## WHEREIN R 1  is selected from the group consisting of alkyl, cycloalkyl, alkenyl, haloalkyl, alkoxy, alkylthio, alkylsulfonyl and alkylsulfinyl; R 2  is selected from the group consisting of alkyl, alkenyl, haloalkyl and ##STR2## wherein R 3  and R 4  are each selected from the group consisting of hydrogen and alkyl; X is selected from the group consisting of alkyl and halogen; and n is an integer from 0 to 3. Further disclosed is the herbicidal utility of the foregoing compounds.

This invention relates to new compositions of matter and more specifically relates to new chemical compounds of the formula ##STR3## wherein R¹ is selected from the group consisting of alkyl, cycloalkyl, alkenyl, haloalkyl, alkoxy, alkylthio, alkylsulfonyl and alkylsulfinyl; R² is selected from the group consisting of alkyl, alkenyl, haloalkyl and ##STR4## wherein R³ and R⁴ are each selected from the group consisting of hydrogen and alkyl; X is selected from the group consisting of alkyl and halogen; and n is an integer from 0 to 3.

The compounds of the present invention are unexpectedly useful as herbicides.

In a preferred embodiment of this invention R¹ is selected from the group consisting of lower alkyl, cycloalkyl of from 3 to 7 carbon atoms, lower alkenyl, lower haloalkyl, lower alkoxy, lower alkylthio, lower alkylsulfonyl and lower alkylsulfinyl; R² is selected from the group consisting of lower alkyl, lower alkenyl, lower haloalkyl and ##STR5## wherein R³ and R⁴ are hydrogen or alkyl of up to 3 carbon atoms; X is selected from the group consisting of lower alkyl, chlorine and bromine; and n is an integer from 0 to 2.

The term "lower" as used herein designates a straight or branched carbon chain of up to six carbon atoms.

The compound of the present invention can be prepared by reacting a compound of the formula ##STR6## wherein R¹ and R² are as heretofore described, with an acid chloride of the formula ##STR7## wherein Y and n are as heretofore described, in the presence of an acid acceptor such as a tertiary amine. This reaction can be effected by slowly adding the acid chloride of formula III with stirring to a solution of an about equimolar amount of the compound of formula II in an inert organic solvent, in the presence of an acid acceptor and at a temperature of about 10° to 30° C. After the addition is completed, the reaction mixture can be heated at a temperature ranging up to the reflux temperature of the mixture to ensure completion of the reaction. The desired product can then be recovered by first filtering the reaction mixture to remove acid acceptor chloride, followed by stripping off the solvent if the product is soluble therein, or, if formed as a precipitate, by filtration and subsequent washing and purification.

The compounds of formula II can be readily prepared by heating a compound of the formula ##STR8## wherein R¹ and R² are as heretofore described, in a dilute, aqueous, acidic reaction medium for a period of about 10 to about 60 minutes. Temperatures of from about 70° C. to the reflux temperature of the reaction mixture can be utilized. The reaction medium can comprise a dilute aqueous inorganic acid such as hydrochloric acid at a concentration of from about 0.5 to about 5 percent. Upon completion of the reaction the desired product can be recovered as a precipitate by cooling the reaction mixture. This product can be used as such or can be further purified by conventional means such as recrystallization and the like.

The compounds of formula IV can be prepared by reacting a molar amount of an isocyanate dimer of the formula ##STR9## wherein R¹ is as heretofore described, with about two molar amounts of a dimethyl acetal of the formula ##STR10## wherein R² is as heretofore described. This reaction can be effected by heating a mixture of the isocyanate dimer and the acetal in an inert organic reaction medium such as benzene at the reflux temperature of the reaction mixture. Heating at reflux can be continued for a period of from about 2 to about 30 minutes to ensure completion of the reaction. After this time the desired product can be recovered upon evaporation of the reaction medium and can be used as such or can be further purified by standard techniques in the art.

The isocyanate dimer of formula V can be prepared by reacting a thiadiazole of the formula ##STR11## wherein R¹ is as heretofore described, with phosgene. This reaction can be effected by adding a slurry or solution of the thiadiazole, in a suitable organic solvent such as ethyl acetate, to a saturated solution of phosgene in an organic solvent such as ethyl acetate. The resulting mixture can be stirred at ambient temperatures for a period of from about 4 to about 24 hours. The reaction mixture can then be purged with nitrogen gas to remove unreacted phosgene. The desired product can then be recovered by filtration, if formed as a precipitate, or upon evaporation of the organic solvent used if soluble therein. This product can be used as such or can be further purified as described.

Exemplary thiadiazoles of formula VII useful for preparing the compounds of the present invention are 5-methyl-2-amino-1,3,4thiadiazole, 5-ethyl-2-amino-1,3,4-thiadiazole, 5-propyl-2-amino-1,3,4-thiadiazole, 5-t-butyl-2-amino-1,3,4-thiadiazole, 5-allyl-2-amino-1,3,4-thiadiazole, 5-pent-3-enyl-2-amino-1,3,4-thiadiazole, 5-chloromethyl-2-amino-1,3,4-thiadiazole, 5-β-chloroethyl-2-amino-1,3,4-thiadiazole, 5-γ-chloropropyl-2-amino-1,3,4-thiadiazole, 5-trichloromethyl-2-amino-1,3,4-thiadiazole, 5-trifluoromethyl-2-amino-1,3,4-thiadiazole, 5-methoxy-2-amino-1,3,4-thiadiazole, 5-ethoxy-2-amino-1,3,4-thiadiazole, 5-propoxy-2-amino-1,3,4-thiadiazole, 5-butyloxy-2-amino-1,3,4-thiadiazole, 5-hexyloxy-2-amino-1,3,4-thiadiazole, 5-methylthio-2-amino-1,3,4-thiadiazole, 5-ethylthio-2-amino-1,3,4-thiadiazole, 5-propylthio-2-amino-1,3,4-thiadiazole, 5-butylthio-2-amino-1,3,4-thiadiazole, 5-methylsulfonyl-2-amino-1,3,4-thiadiazole, 5-ethylsulfonyl-2-amino-1,3,4-thiadiazole, 5-butylsulfonyl-2-amino-1,3,4-thiadiazole, 5-methylsulfinyl-2-amino-1,3,4-thiadiazole, 5-ethylsulfinyl-2-amino-1,3,4-thiadiazole, 5-propylsulfinyl-2-amino-1,3,4-thiadiazole, 5-butylsulfinyl-2-amino-1,3,4-thiadiazole and the like.

Exemplary suitable acetals of formula VI for preparing the compounds of this invention are the dimethyl acetal of 2-methylaminoacetaldehyde, the dimethyl acetal of 2-ethylaminoacetaldehyde, the dimethyl acetal of 2-propylaminoacetaldehyde, the dimethyl acetal of 2-butylaminoacetaldehyde, the dimethyl acetal of 2-pentylaminoacetaldehyde and the dimethyl acetal of 2-hexylaminoacetaldehyde.

Exemplary suitable acid chlorides of formula III useful for preparing the compounds of the present invention are the acid chlorides of the following acids: nicotinic acid, 2-chloronicotinic acid, 6-chloronicotinic acid, 2-methylnicotinic acid, 5-ethylnicotinic acid, 4-propylnicotinic acid, 2-bromonicotinic acid, 6-iodonicotinic acid, 6-fluoronicotinic acid, 2-chloroisonicotinic acid, 6-chloroisonicotinic acid, 3-bromoisonicotinic acid, 5-iodoisonicotinic acid, 6-fluoroisonicotinic acid, 2-methylisonicotinic acid, 2-ethylisonicotinic acid, 3-propylisonicotinic acid, 5-butylisonicotinic acid, 3-methyl-picolinic acid, 3-ethylpicolinic acid, 4-propylpicolinic acid, 4-butylpicolinic acid, 4-chloropicolinic acid, 5-bromopicolinic acid, 6-iodopicolinic acid, 6-fluoropicolinic acid and the like.

The manner in which the compounds of the present invention can be prepared is more specifically illustrated in the following examples.

EXAMPLE 1 Preparation of 5-Methyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-methyl-2-amino-1,3,4-thiadiazole (40 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-methyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 2 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5-methyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-methyl-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-methylaminoacetaldehyde (0.1 mole) and benzene (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-methyl-3-(5-methyl-1,3,4-thiadiazol-2-yl)-ureido]acetaldehyde.

EXAMPLE 3 Preparation of 1-(5-Methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-methyl-3-(5-methyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 4 Preparation of 1-(5-Methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-Methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and nicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 5 Preparation of 5-t-Butyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) was charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-t-butyl-2-amino-1,3,4-thiadiazole (10 grams) in ethyl acetate (300 ml) was added to the reaction vessel, and the resulting mixture was stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture was then purged with nitrogen gas to remove unreacted phosgene. The purged mixture was then filtered to recover the desired product 5-t-butyl-1,3,4-thiadiazol-2-yl isocyanate dimer as a solid having a melting point of 261° to 263° C.

EXAMPLE 6 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5-t-butyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-t-butyl-1,3,4-thiadiazol-2-yl isocyanate dimer (6 grams), the dimethyl acetal of 2-methylaminoacetaldehyde (3.9 grams) and benzene (50 ml) was charged into a glass reaction flask equipped with a mechanical stirrer and reflux condenser. The reaction mixture was heated at reflux, with stirring for a period of about 5 minutes. After this time the reaction mixture was stripped of benzene to yield an oil which solidified upon standing. The resulting solid was then recrystallized from pentane to yield the desired product the dimethyl acetal of 2-[1-methyl-3-(5-t-butyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde having a melting point of 80° to 82° C.

EXAMPLE 7 Preparation of 1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-methyl-3-(5-t-butyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (16 grams), concentrated hydrochloric acid (10 ml) and water (500 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture was heated at reflux for a period of about 15 minutes. The reaction mixture was filtered while hot, and the filtrate was then cooled, resulting in the formation of a precipitate. The precipitate was recovered by filtration, dried and was recrystallized from a benzene-hexane mixture to yield the desired product 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one having a melting point of 133° to 134° C.

EXAMPLE 8 Preparation of 1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture was cooled to a temperature of about 0° C., and nicotinic acid chloride (0.14 mole) was added with stirring. The reaction mixture was allowed to warm to room temperature, and stirring was continued for a period of about 6 hours. After this time the reaction mixture was poured into water (500 ml), resulting in the formation of a solid precipitate. The solid was then recovered by filtration, dried and recrystallized from an ethyl acetate-hexane mixture to yield the desired product 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 9 Preparation of 5-Trifluoromethyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) was charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-trifluoromethyl-2-amino-1,3,4-thiadiazole (45 grams) in ethyl acetate (300 ml) was added to the reaction vessel, and the resulting mixture was stirred for a period of about 16 hours, resulting in the formation of precipitate. The reaction mixture was then purged with nitrogen gas to remove unreacted phosgene. The purged mixture was filtered to recover 48 grams of a white solid. This solid was recrystallized from dimethyl formamide to yield the desired product 5-trifluoromethyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 10 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-trifluoromethyl-1,3,4-thiadiazol-2-yl isocyanate dimer (9.5 grams), the dimethyl acetal of 2-methylaminoacetaldehyde (5.8 grams) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. This product is recrystallized from heptane to yield the desired product the dimethyl acetal of 2-[1-methyl-3-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)ureido]-acetaldehyde having a melting point of 101° to 102° C.

EXAMPLE 11 Preparation of 1-(5-Trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-methyl-3-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture was heated at reflux for a period of about 15 minutes. The reaction mixture was then filtered while hot, and the filtrate was cooled, resulting in the formation of a precipitate. The precipitate was recovered by filtration, was dried and was recrystallized from an ethyl acetate-hexane mixture to yield the desired product 1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one having a melting point of 136° to 138° C.

EXAMPLE 12 Preparation of 1-(5-Trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-Trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and nicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 13 Preparation of 1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-4-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and isonicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-4-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 14 Preparation of 1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-t-Butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and picolinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 15 Preparation of 5-Methoxy-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-methoxy- 2-amino-1,3,4-thiadiazole (40 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-methoxy-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 16 Preparation of the Dimethyl Acetal of 2-[1-Ethyl-3-(5-methoxy-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-methoxy-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-ethylaminoacetaldehyde (0.1 mole) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-ethyl-3-(5-methoxy-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde.

EXAMPLE 17 Preparation of 1-(5-Methoxy-1,3,4-thiadiazol-2-yl)-3-ethyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-ethyl-3-(5-methoxy-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-methoxy-1,3,4-thiadiazol-2-yl)-3-ethyl-5-hydroxy- 1,3-imidazolidin-2-one.

EXAMPLE 18 Preparation of 1-(5-Methoxy-1,3,4-thiadiazol-2-yl)-3-ethyl-5-(2-chloropyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Methoxy-1,3,4-thiadiazol-2-yl)-3-ethyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 2-chloronicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-methoxy-1,3,4-thiadiazol-2-yl)-3-ethyl-5-(2-chloropyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 19 Preparation of 5-Methylthio-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-methylthio-2-amino-1,3,4-thiadiazole (45 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-methylthio-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 20 Preparation of the Dimethyl Acetal of 2-[1-Propyl-3-(5-methylthio-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-methylthio-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-propylaminoacetaldehyde (0.1 mole) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-propyl-3-(5-methylthio-1,3,4-thiadiazol-2-yl)-ureido]acetaldehyde.

EXAMPLE 21 Preparation of 1-(5-Methylthio-1,3,4-thiadiazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-propyl-3-(5-methylthio-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-methylthio-1,3,4-thiadiazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 22 Preparation of 1-(5-Methylthio-1,3,4-thiadiazol-2-yl)-3-propyl-5-pyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-Methylthio-1,3,4-thiadiazol-2-yl)-3-propyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and picolinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-methylthio-1,3,4-thiadiazol-2-yl)-3-propyl-5-pyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one.

EXAMPLE 23 Preparation of 5-Methylsulfonyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-methylsulfonyl-2-amino-1,3,4-thiadiazole (50 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-methylsulfonyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 24 Preparation of the Dimethyl Acetal of 2-[1-Allyl-3-(5-methylsulfonyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-methylsulfonyl-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-allylaminoacetaldehyde (0.1 mole) and benzene (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-allyl-3-(5-methylsulfonyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde.

EXAMPLE 25 Preparation of 1-(5-Methylsulfonyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-allyl-3-(5-methylsulfonyl- 1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-methylsulfonyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 26 Preparation of 1-(5-Methylsulfonyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-(3-methylpyrid-4-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Methylsulfonyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 3-methylisonicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml) resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-methylsulfonyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-(3-methylpyrid-4-ylcarbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 27 Preparation of 5-Methylsulfinyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-methylsulfinyl-2-amino-1,3,4-thiadiazole (50 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-methylsulfinyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 28 Preparation of the Dimethyl Acetal of 2-[1-Chloromethyl-3-(5-methylsulfinyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-methylsulfinyl-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-chloromethylaminoacetaldehyde (0.1 mole) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield the desired product the dimethyl acetal of 2-[1-chloro-methyl-3-(5-methylsulfinyl-1,3,4-thiadiazol-2-yl)ureido]-acetaldehyde.

EXAMPLE 29 Preparation of 1-(5-Methylsulfinyl-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-chloromethyl-3-(5-methylsulfinyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-methylsulfinyl-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 30 Preparation of 1-(5-Methylsulfinyl-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5-(4-bromopyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one

1-(5-Methylsulfinyl-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5 -hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 4-bromopicolinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-methylsulfinyl-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5-(4-bromopyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 31 Preparation of 5-Cyclopropyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) was charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-cyclopropyl-2-amino-1,3,4-thiadiazole (6 grams) in ethyl acetate (100 ml) was added to the reaction vessel, and the resulting mixture was stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture was then purged with nitrogen gas to remove unreacted phosgene. The purged mixture was filtered to recover the desired product 5-cyclopropyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 32 Preparation of the Dimethyl Acetal of 2-[1-Propargyl-3-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-cyclopropyl-1,3,4-thiadiazol-2-yl isocyanate dimer (7 grams), the dimethyl acetal of 2-propargylaminoacetaldehyde (5 grams) and ethyl acetate (50 ml) were charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 2 hours. After this time the mixture is stripped of solvent under reduced pressure to yield the desired product the dimethyl acetal of 2-[1-propargyl-3-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde as an oil.

EXAMPLE 33 Preparation of 1-(5-Cyclopropyl-1,3,4-thiadiazol-2-yl)-3-propargyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-propargyl-3-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde obtained in Example 32, water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized from ethyl acetate to yield the desired product 1-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)-3-propargyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 34 Preparation of 1-(5-Cyclopropyl-1,3,4-thiadiazol-2-yl)-3-propargyl-5-(6-fluoropyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Cyclopropyl-1,3,4-thiadiazol-2-yl)-3-propargyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 6-fluoropicolinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-cyclopropyl-1,3,4-thiadiazol-2-yl)-3-propargyl-5-(6-fluoropyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 35 Preparation of 5-Cyclohexyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (500 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. 5-Cyclohexyl-2-amino-1,3,4-thiadiazole (6 grams) is added to the reaction vessel, and the resulting mixture is stirred and heated at reflux for a period of about 4 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized from a dimethyl formamide-water mixture to yield the desired product 5-cyclohexyl-1,3,4-thiadiazol-2-yl isocyanate dimer having a melting point of 237° to 239° C.

EXAMPLE 36 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-cyclohexyl-1,3,4-thiadiazol-2-yl isocyanate dimer (12 grams), the dimethyl acetal of 2-methylaminoacetaldehyde (6.9 grams) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized from methanol to yield the desired product the dimethyl acetal of 2-[1-methyl-3-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde having a melt point of 133° to 134° C.

EXAMPLE 37 Preparation of 1-(5-Cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-methyl-3-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized from methanol to yield the desired product 1-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one having a melt point of 154° to 155° C.

EXAMPLE 38 Preparation of 1-(5-Cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-(2,6-dichloropyrid-4-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 2,6-dichloroisonicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-cyclohexyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-(2,6-dichloropyrid-4-yl-carbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 39 Preparation of 5-Cyclobutyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-cyclobutyl-2-amino-1,3,4-thiadiazole (45 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-cyclobutyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 40 Preparation of the Dimethyl Acetal of 2-[1-(1,1-Dimethylprop-2-ynyl)-3-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-cyclobutyl-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 1,1-dimethylprop-2-ynylaminoacetaldehyde (0.1 mole) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-(1,1-dimethylprop-2-ynyl)-3-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde.

EXAMPLE 41 Preparation of 1-(5-Cyclobutyl-1,3,4-thiadiazol-2-yl)-3-(1,1-dimethylprop-2-ynyl)-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-(1,1-dimethylprop-2-ynyl)3-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-3-(1,1-dimethylprop-2-ynyl)-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 42 Preparation of 1-(5-Cyclobutyl-1,3,4-thiadiazol-2-yl)-3-(1,1-dimethylprop-2-ynyl)-5-(4,5-dimethylpyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Cyclobutyl-1,3,4-thiadiazol-2-yl)-3-(1,1-dimethylprop-2-ynyl)-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 4,5-dimethylnicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-3-(1,1-dimethylprop-2ynyl)-5-(4,5-dimethylpyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one.

EXAMPLE 43 Preparation of 5-Allyl-1,3,4-thiadiazol-2-yl Isocyanate Dimer

A saturated solution of phosgene in ethyl acetate (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer. A slurry of 5-allyl-2-amino-1,3,4-thiadiazole (50 grams) in ethyl acetate (300 ml) is added to the reaction vessel, and the resulting mixture is stirred for a period of about 16 hours, resulting in the formation of a precipitate. The reaction mixture is then purged with nitrogen gas to remove unreacted phosgene. The purged mixture is then filtered to recover the precipitate. The precipitate is then recrystallized to yield the desired product 5-allyl-1,3,4-thiadiazol-2-yl isocyanate dimer.

EXAMPLE 44 Preparation of the Dimethyl Acetal of 2-[1-Methyl-3-(5-allyl-1,3,4-thiadiazol-2-yl)ureido]acetaldehyde

A mixture of 5-allyl-1,3,4-thiadiazol-2-yl isocyanate dimer (0.05 mole), the dimethyl acetal of 2-methylaminoacetaldehyde (0.1 mole) and benzene (60 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. After this time the mixture is stripped of benzene under reduced pressure to yield a solid product as the residue. The residue is then recrystallized to yield the desired product the dimethyl acetal of 2-[1-methyl-3-(5-allyl-1,3,4-thiadiazol-2-yl)-ureido]acetaldehyde.

EXAMPLE 45 Preparation of 1-(5-Allyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one

The dimethyl acetal of 2-[1-methyl-3-(5-allyl-1,3,4-thiadiazol-2 -yl)ureido]acetaldehyde (15 grams), water (400 ml) and hydrochloric acid (4 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser. The reaction mixture is heated at reflux for a period of about 15 minutes. The reaction mixture is then filtered while hot, and the filtrate is cooled to form a precipitate. The precipitate is recovered by filtration, is dried and is recrystallized to yield the desired product 1-(5-allyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one.

EXAMPLE 46 Preparation of 1-(5-Allyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-(5-iodopyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one

1-(5-Allyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-hydroxy-1,3-imidazolidin-2-one (0.11 mole) and pyridine (60 ml) are charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. The mixture is cooled to a temperature of about 0° C., and 5-iodonicotinic acid chloride (0.14 mole) is added with stirring. The reaction mixture is allowed to warm to room temperature, and stirring is continued for a period of about 6 hours. After this time the reaction mixture is poured into water (500 ml), resulting in the formation of a solid precipitate. The solid is then recovered by filtration, is dried and recrystallized to yield the desired product 1-(5-allyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-(5-iodopyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one.

Additional compounds within the scope of the present invention which can be prepared by the procedures detailed in the foregoing examples include 1-(5-ethyl-1,3,4-thiadiazol-2-yl)-3-ethyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-propyl-1,3,4-thiadiazol-2-yl)-3-propyl-5-pyrid-2-yl-carbonyloxy-1,3-imidazolidin-2-one, 1-(5-hexyl-1,3,4-thiadiazol-2-yl)-3-butyl-5-pyrid-4-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-pent-3-enyl-1,3,4-thiadiazol-2-yl)-3-pentyl-5-(3-ethyl-pyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-hex-4-enyl-1,3,4-thiadiazol-2-yl)-3-hexyl-5-(4-propylpyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-β-chloroethyl-1,3,4-thiadiazol-2-yl)-3-allyl-5-(4-hexylpyrid-3-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-γ-chlorobutyl-1,3,4-thiadiazol-2-yl)-3-but-3-enyl-5-(4-fluoropyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-β-bromoethyl-1,3,4-thiadiazol-2-yl)-3-pent-4-enyl-5-(4-iodopyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-β-bromohexyl-1,3,4-thiadiazol-2-yl)-3-hex-4-enyl-5-(4-bromopyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one, 1-(5-ethoxy-1,3,4-thiadiazol-2-yl)-3-chloromethyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-propoxy-1,3,4-thiadiazol-2-yl)-3-β-chloroethyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-butyloxy-1,3,4-thiadiazol-2-yl)-3-β-bromoethyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1 -(5-hexyloxy-1,3,4-thiadiazol-2-yl)-3-γ-chloropropyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-ethylthio-1,3,4-thiadiazol-2-yl)-3-(1,1-diethylprop-2-ynyl)-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-butylthio-1,3,4-thiadiazol-2-yl)-3-(1,1-dipropylprop-2-ynyl)-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-hexylthio-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-ethylsulfonyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-propylsulfonyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-butylsulfonyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-hexylsulfonyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-ethylsulfinyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-propylsulfinyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one, 1-(5-hexylsulfinyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one and the like.

For practical use as herbicides the compounds of this invention are generally incorporated into herbicidal compositions which comprise an inert carrier and a herbicidally toxic amount of such a compound. Such herbicidal compositions, which can also be called formulations, enable the active compound to be applied conveniently to the site of the weed infestation in any desired quantity. These compositions can be solids such as dusts, granules, or wettable powders; or they can be liquids such as solutions, aerosols, or emulsifiable concentrates.

For example, dusts can be prepared by grinding and blending the active compound with a solid inert carrier such as the talcs, clays, silicas, pyrophyllite, and the like. Granular formulations can be prepared by impregnating the compound, usually dissolved in a suitable solvent, onto and into granulated carriers such as the attapulgites or the vermiculites, usually of a particle size range of from about 0.3 to 1.5 mm. Wettable powders, which can be dispersed in water or oil to any desired concentration of the active compound, can be prepared by incorporating wetting agents into concentrated dust compositions.

In some cases the active compounds are sufficiently soluble in common organic solvents such as kerosene or xylene so that they can be used directly as solutions in these solvents. Frequently, solutions of herbicides can be dispersed under super-atmospheric pressure as aerosols. However, preferred liquid herbicidal compositions are emulsifiable concentrates, which comprise an active compound according to this invention and as the inert carrier, a solvent and an emulsifier. Such emulsifiable concentrates can be extended with water and/or oil to any desired concentration of active compound for application as sprays to the site of the weed infestation. The emulsifiers most commonly used in these concentrates are nonionic or mixtures of nonionic with anionic surface-active agents. With the use of some emulsifier systems an inverted emulsion (water in oil) can be prepared for direct application to weed infestations.

A typical herbicidal composition according to this invention is illustrated by the following example, in which the quantities are in parts by weight.

EXAMPLE 47

    ______________________________________                                         Preparation of a Dust                                                          ______________________________________                                         Product of Example 4                                                                            10                                                            Powdered Talc    90                                                            ______________________________________                                    

The above ingredients are mixed in a mechanical grinder-blender and are ground until a homogeneous, free-flowing dust of the desired particle size is obtained. This dust is suitable for direct application to the site of the weed infestation.

The compounds of this invention can be applied as herbicides in any manner recognized by the art. One method for the control of weeds comprises contacting the locus of said weeds with a herbicidal composition comprising an inert carrier and as an essential active ingredient, in a quantity which is herbicidally toxic to said weeds, a compound of the present invention. The concentration of the new compounds of this invention in the herbicidal compositions will vary greatly with the type of formulation and the purpose for which it is designed, but generally the herbicidal compositions will comprise from about 0.05 to about 95 percent by weight of the active compounds of this invention. In a preferred embodiment of this invention, the herbicidal compositions will comprise from about 5 to about 75 percent by weight of the active compound. The compositions can also comprise such additional substances as other pesticides, such as insecticides, nematocides, fungicides, and the like; stabilizers, spreaders, deactivators, adhesives, stickers, fertilizers, activators, synergists, and the like.

The compounds of the present invention are also useful when combined with other herbicides and/or defoliants, dessicants, growth inhibitors, and the like in the herbicidal compositions heretofore described. These other materials can comprise from about 5% to about 95% of the active ingredients in the herbicidal compositions. Use of combinations of these other herbicides and/or defoliants, dessicants, etc. with the compounds of the present invention provide herbicidal compositions which are more effective in controlling weeds and often provide results unattainable with separate compositions of the individual herbicides. The other herbicides, defoliants, dessicants and plant growth inhibitors, with which the compounds of this invention can be used in the herbicidal compositions to control weeds, can include chlorophenoxy herbicides such as 2,4-D, 2,4,5-T, MCPA, MCPB, 4(2,4-DB), 2,4-DEB, 4-CPB, 4-CPA, 4-CPP, 2,4,5-TB, 2,4,5-TES, 3,4-DA, silvex and the like; carbamate herbicides such as IPC, CIPC, swep, barban, BCPC, CEPC, CPPC, and the like; thiocarbamate and dithiocarbamate herbicides such as CDEC, metham sodium, EPTC, diallate, PEBC, perbulate, vernolate and the like; substituted urea herbicides such as norea, siduron, dichloral urea, chloroxuron, cycluron, fenuron, monuron, monuron TCA, diuron, linuron, monolinuron, neburon, buturon, trimeturon and the like; symmetrical triazine herbicides such as simazine, chlorazine, atraone, desmetryne, norazine, ipazine, prometryn, atrazine, trietazine, simetone, prometone, propazine, ametryne and the like; chloroacetamide herbicides such as alpha-chloro-N,N-dimethylacetamide, CDEA, CDAA, alpha-chloro-N-isopropylacetamide, 2-chloro-N-isopropylacetanilide, 4-(chloroacetyl)morpholine, 1-(chloroacetyl)piperidine and the like; chlorinated aliphatic acid herbicides such as TCA, dalapon, 2,3-dichloropropionic acid, 2,2,3-TPA and the like; chlorinated benzoic acid and phenylacetic acid herbicides such as 2,3,6-TBA, 2,3,5,6-TBA, dicamba, tricamba, amiben, fenac, PBA, 2-methoxy-3,6-dichlorophenylacetic acid, 3-methoxy-2,6-dichlorophenylacetic acid, 2-methoxy-3,5,6-trichlorophenylacetic acid, 2,4-dichloro-3-nitrobenzoic acid and the like; and such compounds as aminotriazole, maleic hydrazide, phenyl mercuric acetate, endothal, biuret, technical chlordane, dimethyl 2,3,5,6-tetrachloroterephthalate, diquat, erbon, DNC, DNBP, dichlobenil, DPA, diphenamid, dipropalin, trifluralin, solan, dicryl, merphos, DMPA, DSMA, MSMA, potassium azide, acrolein, benefin, bensulide, AMS, bromacil, 2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione, bromoxynil, cacodylic acid, CMA, CPMF, cypromid, DCB, DCPA, dichlone, diphenatril, DMTT, DNAP, EBEP, EXD, HCA, ioxynil, IPX, isocil, potassium cyanate, MAA, MAMA, MCPES, MCPP, MH, molinate, NPA, OCH, paraquat, PCP, picloram, DPA, PCA, pyrichlor, sesone, terbacil, terbutol, TCBA, brominil, CP-50144, H-176-1, H-732, M-2901, planavin, sodium tetraborate, calcium cyanamid, DEF, ethyl xanthogen disulfide, sindone, sindone B, propanil and the like. Such herbicides can also be used in the methods and compositions of this invention in the form of their salts, esters, amides, and other derivatives whenever applicable to the particular parent compounds.

Weeds are undesirable plants growing where they are not wanted, having no economic value, and interfering with the production of cultivated crops, with the growing of ornamental plants, or with the welfare of livestock. Many types of weeds are known, including annuals such as pigweed, lambsquarters, foxtail, crabgrass, wild mustard, field pennycress, ryegrass, goose grass, chickweed, wild oats, velvetleaf, purslane, barnyardgrass, smartweed, knotweed, cocklebur, wild buckwheat, kochia, medic, corn cockle, ragweed, sowthistle, coffeeweed, croton, cuphea, dodder, fumitory, groundsel, hemp nettle, knawel, spurge, spurry, emex, jungle rice, pondweed, dog fennel, carpetweed, morningglory, bedstraw, ducksalad, naiad, cheatgrass, fall panicum, jimsonweed, witchgrass, switchgrass, watergrass, teaweed, wild turnip and sprangletop; biennials such as wild carrot, matricaria, wild barley, campion, chamomile, burdock, mullein, roundleaved mallow, bull thistle, hounds-tongue, moth mullein and purple star thistle; or perennials such as white cockle, perennial ryegrass, quackgrass, Johnsongrass, Canada thistle, hedge bindweed, Bermuda grass, sheep sorrel, curly dock, nutgrass, field chickweed, dandelion, campanula, field bindweed, Russian knapweed, mesquite, toadflax, yarrow, aster, gromwell, horsetail, ironweed, sesbania, bulrush, cattail, winter-cress, horsenettle, nutsedge, milkweed and sicklepod.

Similarly, such weeds can be classified as broadleaf or grassy weeds. It is economically desirable to control the growth of such weeds without damaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weed control because they are toxic to many species and groups of weeds while they are relatively nontoxic to many beneficial plants. The exact amount of compound required will depend on a variety of factors, including the hardiness of the particular weed species, weather, type of soil, method of application, the kind of beneficial plants in the same area and the like. Thus, while the application of up to only about one or two ounces of active compound per acre may be sufficient for good control of a light infestation of weeds growing under adverse conditions, the application of ten pounds or more of an active compound per acre may be required for good control of a dense infestation of hardy perennial weeds growing under favorable conditions.

The herbicidal toxicity of the new compounds of this invention can be demonstrated by the following established testing techniques known to the art, pre- and post-emergence testing.

The herbicidal activity of the compounds of this invention can be demonstrated by experiments carried out for the pre-emergence control of a variety of weeds. In these experiments small plastic greenhouse pots filled with dry soil are seeded with the various weed seeds. Twenty-four hours or less after seeding the pots are sprayed with water until the soil is wet and a test compound formulated as an aqueous emulsion of an acetone solution containing emulsifiers is sprayed at the desired concentrations on the surface of the soil.

After spraying, the soil containers are placed in the greenhouse and provided with supplementary heat as required and daily or more frequent watering. The plants are maintained under these conditions for a period of from 15 to 21 days, at which time the condition of the plants and the degree of injury to the plants is rated on a scale of from 0 to 10, as follows: 0= no injury, 1,2= slight injury, 3,4= moderate injury, 5,6= moderately severe injury, 7,8,9= severe injury and 10= death.

The herbicidal activity of the compounds of this invention can also be demonstrated by experiments carried out for the post-emergence control of a variety of weeds. In these experiments the compounds to be tested are formulated as aqueous emulsions and sprayed at the desired dosage on the foliage of the weeds that have attained a prescribed size. After spraying the plants are placed in a greenhouse and watered daily or more frequently. Water is not applied to the foliage of the treated plants. The severity of the injury is determined 10 to 15 days after treatment and is rated on the scale of from 0 to 10 heretofore described. 

I claim:
 1. A compound of the formula ##STR12## wherein R¹ is selected from the group consisting of lower alkyl, cycloalkyl of from 3 to 7 carbon atoms, lower alkenyl, lower haloalkyl, lower alkoxy, lower alkylthio, lower alkylsulfonyl and lower alkylsulfinyl; R² is selected from the group consisting of lower alkyl, lower alkenyl, lower haloalkyl and ##STR13## wherein R³ and R⁴ are each selected from the group consisting of hydrogen and alkyl of up to 3 carbon atoms; X is selected from the group consisting of lower alkyl, chlorine and bromine; and n is an integer from 0 to
 3. 2. The compound of claim 1, 1-(5-methyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.
 3. The compound of claim 1, 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.
 4. The compound of claim 1, 1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-3-ylcarbonyloxy-1,3-imidazolidin-2-one.
 5. The compound of claim 1, 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-4-ylcarbonyloxy-1,3-imidazolidin-2-one.
 6. The compound of claim 1, 1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-4-ylcarbonyloxy-1,3-imidazolidin-2-one.
 7. The compound of claim 1, 1-(5-t-butyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-2-ylcarbonyloxy)-1,3-imidazolidin-2-one.
 8. The compound of claim 1, 1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)-3-methyl-5-pyrid-2-ylcarbonyloxy-1,3-imidazolidin-2-one.
 9. A herbicidal composition comprising an inert carrier and, as an essential active ingredient, in a quantity toxic to weeds, a compound of claim
 1. 10. A method of controlling weeds which comprises contacting said weeds with a herbicidal composition comprising an inert carrier and, as an essential active ingredient, in a quantity toxic to weeds, a compound of claim
 1. 